The MOCVD (Metal Organic Chemical Vapor Deposition) method is a vacuum film forming technique which forms a thin film on a substrate by the heat decomposition of organic metal gas having high reactivity, or by the direct reaction of the organic metal gas with other gas. The MOCVD method is expected to be applied to the electronics field including metal circuit layer forming technique.
FIG. 5 shows a schematic view of a source gas supply line of a prior art MOCVD apparatus.
Organic metal complex in the liquid state (liquid raw material) 1 is stored in a closed vessel 2. A gas feed line 3 for pneumatic transportation is connected with the closed vessel 2. A transport gas, for example helium (He), is introduced into the closed vessel 2 through a valve 4. A delivery line 5 is connected with the closed vessel 2. The liquid raw material 1 is delivered to the outside of the closed vessel 2 through the delivery line 5 by introducing the transport gas into the closed vessel 2. The delivery line 5 is connected to a vaporizer 10 through a liquid raw material feed line 9 which comprises a valve 6, a mass flow controller (MFC) 7 and a valve 8.
The vaporizer 10 is vacuum equipment (component for vacuum apparatus) which vaporizes the liquid raw material 1 supplied through the liquid raw material feed line 9 and then forms a source gas by mixing the liquid raw material and a carrier gas such as argon (Ar). The carrier gas is supplied to the vaporizer 10 through a carrier gas feed line 11 which comprises a valve 12, a mass flow controller (MFC) 13 and a valve 14.
A pipe member 17 and a valve 19 are connected between the vaporizer 10 and a reaction chamber (film forming chamber) 15. The source gas formed by the vaporizer 10 is introduced into the reaction chamber 15 through the pipe member 17 and the valve 19. The vaporizer 10, the pipe member 17 and the valve 19 are heated at a predetermined temperature with heating unit 20 for vaporizing the raw material.
A part of or the whole of the pipe member 17 is coil shaped so as to be able to transform elastically when joining the valve 19 to the vaporizer 10, so that the joining operation of these members becomes easy. Accordingly, not only this pipe member 17 but also the other pipe members, such as the liquid raw material feed line 9 and the carrier gas feed line 11, can adopt a similar construction.
The reaction chamber 15 is depressurized at a predetermined degree of vacuum with a vacuum pump 16. A stage 18 having a heater for heating a substrate W to be processed, such as a semiconductor wafer or a glass substrate for liquid crystal device, is installed in this reaction chamber 15. In the reaction chamber 15, the source gas is decomposed by reacting with a reaction gas such as ammonia or hydrogen which is introduced into the reaction chamber 15 simultaneously, and then a metal layer is formed on the substrate W.
Many of the organic metal materials for forming a film by the MOCVD method are typically in a liquid or solid state at room temperature (25.). Accordingly, when organic metal material is used as raw material for chemical vapor deposition (CVD) or atom layer deposition (ALD), pipelines for transporting vaporized metal organic material and valves are held at a temperature higher than room temperature (refer to Patent Document 1).
Patent Document 1: JP2001-11631A
Patent Document 2: JP 4-341559A